1. Field of the Invention
The invention relates to an electrophotographic image forming apparatus and a process cartridge detachably mountable on the electrophotographic image forming apparatus.
Here, the electrophotographic image forming apparatus is an apparatus for recording an image on a recording medium by the use of an electrophotographic image forming process, and this term covers, for example, an electrophotographic copying machine, an electrophotographic printer (such as, for example, a laser beam printer or an LED printer), a facsimile apparatus and a word processor or the like.
Also, the process cartridge refers to at least one of charging means, developing means and cleaning means and an electrophotographic image bearing member integrally made into a cartridge, which is made detachably mountable on a main body of an image forming apparatus.
2. Description of the Related Art
An electrophotographic image forming apparatus such as a copying machine, a laser beam printer or a facsimile apparatus effects selective exposure on an electrophotographic photosensitive drum which is an image bearing member uniformly charged by a charging device to thereby form an electrostatic latent image thereon. This electrostatic latent image is then developed as a toner image by a toner being caused to adhere thereto by a developing device, whereafter this toner image is transferred to a recording material such as paper to thereby form an image. The image bearing member after the transfer of the toner image has any residual toner on its surface removed by a cleaning device, and is used for the next image forming operation.
In recent years, there are known the image bearing member, the charging device, the developing device, the cleaning device, etc. integrally incorporated into a cartridge container and made into a process cartridge. This process cartridge is designed to be detachably mountable on a main body of an image forming apparatus. Consequently, a user can mount it on the image forming apparatus main body to thereby simply effect the supply of the toner and the interchange of the image bearing member by himself, thus achieving the ease of maintenance.
Further in recent years, there has also been devised an image forming apparatus for forming a multi-color image, and a process cartridge for use in such multi-color image forming apparatus has also been put into practical use.
As developing means in the above-described process cartridge, there are generally known two types, i.e., a contact developing type which effects development with a developer carrying member brought into contact with the image bearing member, and a non-contact developing type which effects development with a developer carrying member spaced apart by a predetermined gap from the image bearing member.
The developing means of the above-described contact type, however, if left in contact with the image bearing member for a long period, has sometimes affected an image with that portion of the developing means which contacts with the image bearing member being deformed. Also on the surface of the image bearing member, the image bearing member and the developing means frictionally contact each other due to the vibration or the like during the transportation of the process cartridge, and a hysteresis remains as a development memory, and this has sometimes affected an image.
As means for avoiding the above-noted problems, there have heretofore been proposed an image forming apparatus and a process cartridge of a construction provided with a mechanism for separating the image bearing member and the developing means from each other during non-use such as shipping or the long-term stoppage of use (U.S. Patent Publication No. 2003/0185587). The conventional separating member is of a construction which grasps the frame of the process cartridge against a developing biasing member to thereby separate the developing means from the image bearing member.
The present invention is further development of the conventional art.